Electrolysis of solid metal sulfide to metal and sulfur in molten NaCl–KCl

Abstract Electrochemical desulfidation of solid sulfide has been studied for the first time in the mixed NaCl–KCl melt. At 700 °C, the equimolar NaCl–KCl enabled highly efficient transport of the S 2− ion and high speed electro-reduction of porous WS 2 pellets to W nanonodules (50–100 nm). The graphite anode was experimentally confirmed to be an ideal non-consumable anode, on which the S 2− ion was oxidised to gaseous sulfur. The current efficiency of the electrolysis of WS 2 was higher than 90% and the energy consumption could be lower than 1.23 kWh/kg-W. These findings promise new green methods for the preparation of various transition metals and alloys by electro-desufidation of their solid sulfides.